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Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thrombolytic therapy has been shown to reduce mortality after acute myocardial infarction. Great efforts have been undertaken in the past decade to develop more efficient thrombolytic regimens. Novel recombinant thrombolytic substances have been engineered. Reteplase, a deletion mutant of wild-type tissue plasminogen activator with a longer half-life, has been evaluated in clinical trials and is now available for clinical use. In the randomised Reteplase Angiographic Phase II International Dose-Finding (RAPID-1) trial, involving 606 patients with acute myocardial infarction, a double-bolus regimen of reteplase (10 + 10U given 30 minutes apart) achieved significantly higher patency rates at 90 minutes after initiation of thrombolytic therapy than a 10 + 5U double-bolus reteplase regimen, a 15U single bolus reteplase regimen, or a conventional alteplase regimen (100mg in 180 minutes). In the Reteplase versus Alteplase Patency Investigation During Acute Myocardial Infarction (RAPID-2) trial, the reteplase 10 + 10U double-bolus regimen was more effective with regard to patency at 60 and 90 minutes than accelerated alteplase (100mg in 90 minutes). The International Joint Efficacy Comparison of Thrombolytics (INJECT) trial showed that a double-bolus regimen of reteplase 10 + 10U was at least equivalent to streptokinase in terms of 35-day mortality rate. The third Global Utilization of Strategies to Open Occluded Coronary Arteries (GUSTO-III) trial resulted in similar 30-day mortality after therapy with double-bolus reteplase 10 + 10U (7.47%) or accelerated alteplase (7.24%). Hence, the higher early patency rates achieved with reteplase treatment did not translate into improved survival. Consequently, there is still some uncertainty as to whether or not these drugs are equivalent.
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PMID:Recombinant plasminogen activators: a comparative review of the clinical pharmacology and therapeutic use of alteplase and reteplase. 1802 May 78

In addition to the first generation thrombolytics streptokinase and urokinase there are now a number of new human thrombolytic proteins produced by recombinant techniques. In this review alteplase, saruplase and reteplase are discussed. These compounds differ with respect to their pharmacokinetics. Alteplase and saruplase have relatively short half-lives and are high clearance compounds. Their clearance is dependent upon the hepatic blood flow. This is relevant as myocardial function strongly influences liver blood flow and hence the clearance of alteplase and saruplase. The clearance of reteplase is less dependent upon liver blood flow and is partly dependent on renal excretion. This extends its half-life and reteplase has been successfully administered as a double bolus injection. The question remains if these differences are responsible for any clinical benefits that could not be accomplished by variations in dosage or dosage schedule for a single thrombolytic. Pharmacokinetic differences can only be interpreted if reasonable knowledge exists about the shape and location of the plasma concentration- (adverse) effect curves. This information is not yet available for the recombinant thrombolytic drugs and any clinical differences could well be caused purely by differences in dosage or dosage schedule. It is recommended that plasma concentrations of thrombolytics are measured in future clinical trials, for which techniques are currently available.
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PMID:Pharmacokinetics of the recombinant thrombolytic agents: what is the clinical significance of their different pharmacokinetic parameters? 1803 Nov 20

Thrombolytic agents activate plasminogen and induce a systemic fibrinolytic and anticoagulant state. Two thrombolytic drugs are used frequently in practice: streptokinase (SK) and alteplase (t-PA). Streptokinase mainly undergoes renal elimination with a half-life of 11-17 min, while alteplase is eliminating by the liver with a half-life of 4-6 min. Our goal was to examine whether renal and hepatic function influence the elimination and metabolism of thrombolytics and the efficacy of percutaneous coronary intervention (PCI) after using alteplase or streptokinase. 416 patients with myocardial infarction (MI) were treated from January 2001 to December 2003 (228 male and 189 female). Alteplase was used in 9 men and 6 women (mean age: 53.88 +/- 9.61 vs. 65.33 +/- 9.87 years, p = 0.07). Patients who underwent rescue PCI after administration of alteplase had slightly higher hepatic enzyme levels/alanine transaminase (ALT): 47.85 vs. 41.4 U/l; gamma-glutamyl transpeptidase (GGT): 69.5 vs. 44.8 U/l/. All patients treated with alteplase survived, rescue PCI was done in 8 cases. Streptokinase was used in 36 men and 28 women (mean age: 63.33 +/- 10.51 vs. 63 +/- 12.03 years, p = 0.9). We did not find a difference between serum creatinine levels of patients who received streptokinase and underwent PCI as compared to those who had not. Rescue PCI was done in 16 cases. 12 patients died in this group. In conclusion we have not found a significant correlation between the use of the thrombolytics and hepatic or renal function; this could indicate that such a slight impairment of liver and renal function does not influence pharmacokinetic properties of thrombolytics.
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PMID:Does impairment of renal and hepatic function influence the metabolism of thrombolytics in patients with myocardial infarction? 1844 16

Treatment of acute ischaemic stroke aims to recanalize the occluded artery, salvage the at-risk brain tissue and thus minimize neurological sequelae. Efforts a decade ago have led to the only currently approved medical treatment for acute ischaemic stroke, i.e. intravenous alteplase given within 3 hours of stroke onset. Recanalization occurs in only one-half of the patients receiving alteplase, and only approximately 5% of all ischaemic stroke patients in industrialized countries receive this treatment. Studies are currently being carried out to determine whether intravenous alteplase would be safe and effective for up to 4.5 hours after ischaemic stroke onset, and whether it should be followed by an intra-arterial approach. Two novel thrombolytic drugs being studied for acute ischaemic stroke are desmoteplase and tenecteplase. Although the first trials were promising, the most recent evidence suggests that desmoteplase is not superior to placebo, even in carefully selected patients, in the 3- to 9-hour time window after stroke onset. Tenecteplase has only been studied for acute ischaemic stroke in a single noncontrolled, dose-finding trial in the 3-hour time window after stroke onset, which suggested a similar efficacy to that demonstrated in the historical data from the alteplase trials. A trial to compare the safety and efficacy of tenecteplase versus alteplase is ongoing. Safer and more effective thrombolytic drugs for the treatment of ischaemic stroke are thus being sought. Such agents will be welcome, but they are not here yet. While waiting we are likely to see the emergence of additive therapies, including ultrasound insonation, neuroprotective/regenerative agents and invasive intra-arterial techniques. Novel thrombolytic drugs, or other novel therapies, possess great potential to make a difference in the future, but the most urgent priority now is in the organization of stroke treatment in such a way that more patients receive the currently available optimal treatments.
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PMID:Novel thrombolytic drugs: will they make a difference in the treatment of ischaemic stroke? 1860 1

There are some doubts whether in a severe renal failure the dose of alteplase should not be modified, especially when its plasma clearance may be decreased by liver ischemia. The authors present a case of a 67-year old woman with massive pulmonary embolism (PE) and acute renal failure (creatinine 580 micromol/l) of a mixed etiology (renal calculosis with hydronephrosis and shock as PE presentation). Alteplase administration (10 mg bolus followed by reduced to 50 mg two hours infusion) resulted in hemodynamic stabilization but was complicated by gross subcutaneous hematomas, intensive epistaxis and hematuria, and hemoglobin decrease which required blood transfusions.
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PMID:[Massive pulmonary embolism treated with a reduced dose of alteplase in a patient with acute renal failure]. 1880 42

In Japan, the intravenous tissue plasminogen activator (t-PA) Alteplase (0.6 mg/kg) administration of the within 3 h of the onset of acute ischemic stroke was approved for therapeutic use in the year 2006. t-PA induces thrombolysis in patients with acute ischemic stroke, and this method has gradually gained recognition among physicians and the general population. However, the number of patients who were treated using Alteplase is low (4,000-5,000 patients/year), and this figure accounts for only 2-3% of the annual number of cases of ischemic stroke. There is little doubt that Alteplase treatment is a potentially effective modality for some patients with acute ischemic stroke. The post-marketing surveillance of 4,749 Japanese patients treated using Alteplase showed that 33% of the patients had modified Rankin scale (mRS) scores of 0-1, 17% of patiens died and 4.5% presented with symptomatic intracerebral hemorrhage (ICH); these results were comparable to those from other countries. The expansion of the therapeutic time window has been a matter of concern. The investigators of the European Cooperative Acute Stroke Study (ECASS) have reported that there was significant improvement in the clinical outcomes of patients with acute ischemie stroke when Alteplase was administered 3-4.5 h after the onset of the symptoms. Mismatches in perfusion- and diffusion-weighted (DW) magnetic resonance imaging (MRI) images have been used for selecting patients 3 h after the onset of symptoms, and the findings from MRI, dwimages (DWI) and MR angiography are practical predictors of t-PA therapy within 3 h of onset. The Middle Cerebral Artery Embolism Local Fibrinolytic Intervention Trial (MELT) Japan study showed that local intra-arterial fibrinolysis is effective in patients with embolic MCA occlusion within 6 h of the onset of symptoms. Combining the initiation of intravenous t-PA administration with further intra-arterial fibrinolysis or mechanical thrombolectomy may improve the recanalization rate. Thrombolysis in combination with ultrasound-enhanced clot lysis is another attractive therapy. In Japan the neuroprotective agent edaravone (radical scavenger) is commonly used in combination with t-PA, and it is expected to decrease the hemorrhagic transformation after t-PA administration. Acute cerebral ischemic symptoms may occasionally precede thoracic aortic dissection. Thoracic aortic dissection after t-PA administration may prove to be fatal, and it is an important disorder that must be differentially diagnosed.
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PMID:[Thrombolysis by intravenous tissue plasminogen activator (t-PA)--current status and future direction]. 1917 6

Japan Alteplase Clinical Trial (J-ACT), a prospective multicenter clinical trial, demonstrated good clinical outcome in patients treated with 0.6 mg/kg of alteplase, being similar to that with 0.9 mg/kg of alteplase in the National Institute of Neurological Disorders and Stroke (NINDS) study. On that basis, intravenous aplteplase therapy was approved in Japan in October, 2005. This therapy resulted in better efficacy and similar safety in our stroke care unit (SCU) as compared to J-ACT or other clinical studies performed outside Japan. Our nation-wide survey demonstrated that the approval of the therapy resulted in dramatic changes in the processes of management for acute stroke patients. Preliminary results of the post-marketing surveillance study of alteplase in Japan suggested similar efficacy and safety profiles of the therapy to those reported by a European study, Safe Implementation of Thrombolysis in Stroke-Monitoring Study (SITS-MOST). There are several limitations and problems in the therapy that will be overcome by new therapeutic strategies including the development of new-generation therombolytic agents having longer therapeutic time window, applications of magnetic resonance imaging techniques, and combination therapies with neuroprotective agents, sonothrombolysis, intraarterial application of the agent, or mechanical thrombectomy.
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PMID:[New era has begun since the approval of thrombolytic therapy for acute ischemic stroke in Japan]. 1919 7

Alteplase is standard therapy for patients with acute, massive pulmonary embolism. The novel plasminogen activator desmoteplase displays high fibrin specificity and selectivity for fibrinbound plasminogen. In a preclinical model desmoteplase was twice as potent with a shorter lysis time and lower reocclusion rate. We conducted a phase II study comparing 125, 180, and 250 microg/kg bodyweight desmoteplase with 100 mg alteplase. Efficacy criteria were total pulmonary resistance (TPR), mean pulmonary artery pressure (mPAP), and Miller Index. Intention to treat analysis of 34 patients. The reduction of TPR after 24 hours was comparable between desmoteplase 180 microg/kg and alteplase (-48.0 +/- 22.4 vs. -50.4 +/- 16.3%; p = n.s. vs. alteplase; p = 0.0002 and p<0.0001 vs. baseline). The greatest effect was achieved with desmoteplase 250 microg/kg (-56.0 +/- 29.4%; p = n.s. vs. alteplase, p = 0.0055 vs. baseline). Two hours after treatment PAP was reduced by 27.9 (p = 0.0004 vs. baseline) and 30.4% (p = 0.015 vs. baseline) with the higher doses of desmoteplase and 29.6% with alteplase (p = 0.0006 vs. baseline). Further PAP reduction after 6 hours was most pronounced in the desmoteplase 250 microg/kg group (-40.1 +/- 18.0%; p = 0.0028 vs. baseline). The reduction of the Miller Index was greatest using desmoteplase 250 microg/kg (-35.0 +/- 21.7%; p = 0.011 vs. baseline), and alteplase (-41.6 +/- 27.2%; p = 0.0003 vs. baseline). Safety did not differ among the 4 groups. The study results suggest that desmoteplase at doses of 180 and 250 microg/kg had similar or greater efficacy compared to alteplase 100 mg. Onset of action was faster, safety was comparable.
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PMID:Desmoteplase in acute massive pulmonary thromboembolism. 1927 20

TNKase is a genetically engineered variant of the alteplase molecule. Three different mutations result in an increase of the plasma half-life, of the resistance to plasminogen-activator inhibitor 1 and of the thrombolytic potency against platelet-rich thrombi. Among available agents in clinical practice, TNKase is the most fibrin-specific molecule and can be delivered as a single bolus intravenous injection. Several large-scale clinical trials have enrolled more than 27,000 patients with acute myocardial infarction, making the use of this drug truly evidence-based. TNKase is equivalent to front-loaded alteplase in terms of mortality and is the only bolus thrombolytic drug for which this equivalence has been formally demonstrated. TNKase appears more potent than alteplase when symptoms duration lasts more than 4 hours. Also, TNKase significantly reduces the rate of major bleeds and the need for blood transfusions. The efficacy of TNKase may be further improved by enoxaparin substitution for unfractionated heparin, provided that enoxaparin dose adjustment is made for patients more than 75 years old. Hitherto, the small available randomized studies and international clinical registries suggest that pre-hospital TNKase is as effective as primary angioplasty, thus laying the foundations for a new fibrinolytic, TNKase-based strategy as the backbone of reperfusion in acute myocardial infarction.
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PMID:Review of tenecteplase (TNKase) in the treatment of acute myocardial infarction. 1943 56

The US Food and Drug Administration (FDA) approved the use of intravenous (IV) recombinant tissue plasminogen activator (rt-PA) in 1996, on the basis of the results of the National Institute of Neurological Disorders and Stroke (NINDS) rt-PA Stroke Study. IV rt-PA therapy at a dose of 0.9 mg/kg has been approved internationally for the treatment of hyperacute ischemic stroke. After a dose comparison study using duteplase and a multicenter study using a single dose of alteplase (Japan Alteplase Clinical Trial: J-ACT), the administration of IV rt-PA therapy at a dose of 0.6 mg/kg was approved in Japan in 2005. Immediately after the approval, the Japan Stroke Society published the Japanese guidelines for this low-dose therapy. Two years after the approval in Japan, the outcome of IV rt-PA therapy in Japan was observed to be comparable to that of NINDS rt-PA therapy and to those published in studies based in Western nations. Several trials have reported predictors of unfavorable outcome for IV rt-PA therapy. Patients with severe strokes (higher NIHSS score, coma), higher age at disease onset, aortic arch dissection, higher blood pressure, higher blood sugar, occlusion of the internal carotid artery (ICA) or tandem lesion of the left ICA and right middle cerebral artery (MCA), or the presence of major early ischemic changes as observed upon computed tomography (CT) or magnetic resonance imaging (MRI), showed a greater probability for unfavorable response to treatment. The results of the randomised 2008 trial conducted by the third European Cooperative Acute Stroke Study (ECASS III) suggested that treatment with IV rt-PA administered 3-4.5 hours after symptom onset can still induce significant improvement in clinical outcomes after an acute ischemic stroke as opposed to a placebo. MRI-based thrombolysis might be safer than standard CT-based thrombolysis. A combination of reperfusion therapies, IV rt-PA and sonothrombolysis, neuroprotective agents or antiplatelet agents may be effective. However, currently available data do not provide conclusive evidence for the safety or efficacy of these combination therapies. Patients having ICA occlusion may require alternatives including a higher dose of alteplase, combined IV/IA thrombolysis, or possibly mechanical thrombectomy by using a thrombus-removal device.
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PMID:[Prospects of thrombolytic therapy for acute ischemic stroke]. 1980 99


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